Energy Efficiency Made Simple Vol IV 2015

IEC/EN 62305 2006: Lightning protection standard IEC/EN 62305-1: General principles IEC/EN 62305-2: Risk management IEC/EN 62305-3:

Physical damage to structures and life hazard Electric and electronic systems within structures

IEC/EN 62305-4:

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approaches can be derived from the relevant protection standards: • Material damage and life hazard in case of direct lightning strikes to a structure can be minimised by a conventional Lightning Protection System (LPS) according to IEC/EN 62305-3 [3] • To ensure protection of structures with electrical and electronic systems, particularly if reliable operation and supply are essential, these systems must be additionally protected from conducted and radiated interference resulting from the Lightning Electromagnetic Pulse (LEMP) in case of direct and indirect lightning strikes. This can be achieved by a LEMP protection system according to IEC/EN 62305-4 [3] A detailed risk assessment of the local threat potential (both for power supply and information technology and communication systems) is required to efficiently protect the technologies used for modern grid expansion such as intelligent transformer substations [4], monitoring and telecontrol systems, adjustable regulated distribution transformers or longitudinal voltage controllers from the sources of damage. This involves certain challenges, for example, lightning and surge protection measures for the electronic components, lacking ease of maintenance and the frequently compact design of the systems. According to the IEC/EN 62305-2 [3] standard, the total risk of lightning damage consists of the frequency of a lightning strike, the probability of damage and the loss factor. If the technologies men- tioned are assessed according to these criteria in conjunction with practical experiences, you will get different individual results depending on the local thunderstorm activity, design and place of installation. To prevent galvanic coupling to the 20 kV medium-voltage overhead Possible solution approaches and criteria for selecting arresters

line network or outgoing low-voltage lines as a result of a direct lightning strike, a protective device must be installed in the main low-voltage distribution board. This protective device must be selected in such a way that it meets the requirements concerning the lightning current carrying capability, short-circuit strength, follow current extin- guishing capability and Temporary OverVoltages (TOV) characteristic. A spark-gap-based Type 1 combined arrester with integrated back-up fuse (CI technology or Circuit Interruption Fuse Integrated) is ideally suited for this purpose. This integrated back-up fuse significantly saves space and installation work compared to a separate arrester back-up fuse and is adapted to the discharge capacity of the spark gap. This ensures maximum performance and incorrect installation is avoided. If only indirect lightning effects such as inductive or capacitive coupling, conducted partial lightning currents or SEMP are to be expected for the secondary technology according to a risk analysis as per IEC/EN 62305-2 [3], Type 2 (sub-distribution board) and Type 3 (protection of terminal devices) surge arresters are sufficient. Type 2 arresters with the compact CI technology described are available for restricted space conditions. A surge arrester with integrated Lifetime Indication can be used to implement a preventive maintenance concept. This Lifetime Indi- cation detects pre-damage and indicates this status at an early stage before the surge protective device fails. The arrester can therefore be integrated in condition monitoring systems. This version has a higher discharge capacity than conventional Type 2 arresters, thus increasing the protective effect. In case of wired signal interfaces, injection is to be expected and therefore these interfaces must be protected. A direct lightning strike to the relevant conductor system or a nearby lightning strike close to the relevant conductor system is possible in this case. Therefore, a risk analysis must be performed and the components

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ENERGY EFFICIENCY MADE SIMPLE 2015